Clinical Study Of ECG Morphological Characteristics And Ventricular Synchronization When Pacing In Different Parts Of Right Ventricular Septal

Object:Through comparative analysis of the QRS morphology、duration and ventricular dyssynchrony when pacing in different parts of right ventricular (RV) septal, Summarize which portion of the RV septum is preferable to the other and then guide the site selection when implant right ventricular electrode.Methods:Patients from June 2014 to Mar 2015 in Nanjing Drum Tower Hospital with an indication for dual-chamber pacing because of atrio-ventricular block were enrolled in this study. Basic clinical information and electrocardiogram (ECG) date were collected before the operation. The pacing parameters were recorded during the operation. After the implantation, in the case of full ventricular pacing,12-lead-ECG and echocardiography was performed in all patients to obtain the pacing QRS duration (PQRSd), the Paced QRS complex vector of leads Ⅰ and Ⅲ, QRS transition in the precordial leads as well as inter-ventricular and intra-ventricular dyssynchrony (IVMD, SPWMD, Tmsvl6-SD, SDI and Which Tmsv16-SD and SDI obtained by three-dimensional echocardiography). Transthoracic echocardiography was used to determine the exact pacing sites for all patients. According to the pacing sites, analysis of the pacing parameters, QRS morphology、duration and ventricular dyssynchrony when pacing in different parts of RV septal.Result:A total of 30 patients were enrolled in this study and 25 patients completed the date collection. According to the results of echocardiography,25 patients were divided into 2 subgroup:the right-ventricular outflow tract septal group(RVOT septum) and right-ventricular inflow tract septal group(RVIT septum). Furthermore, RVIT septal group is further divided into the inflow tract septal of near the apex group and the lower mid-septal group. The results are as follows:1、Both of two groups could acquire satisfactory pacing parameter and there were no significant differences in the RV mean stimulation threshold, R-wave sensing and lead impedance.2、The PQRSd was narrower when pacing from the RVOT septal(147.8±8.7ms VS 150.3±14.0ms; P=0.614), but there were no significant differences. And it was shortest while pacing in the lower mid-septum of RVIT tract, and there were significant differences between the septal of near apex group and the lower mid-septal group(141.67±9.5msVS 156.75±13.7ms; P=0.040);3、The paced QRS complex vector of leads Ⅲ and transition leads were significantly different between the RVOT septal group and RVIT septa] group((P= 0.037 and 0.012, respectively), and the paced QRS complex vector of leads Ⅲ is valuable in predicting the RVOT septal(AUC=0.776, P=0.02); In the septal of near apex group, the QRS complex vector of leads Ⅲ mostly Presented as isoelectric or negative and mostly the precordial leads transform in V6 or later; The paced QRS vector of leads Ⅲ and QRS transition in the precordial leads could predict the right ventricular electrode in septal of near apex(AUC was 0.849 and 0.908, P<0.05, respectively).4、In terms of ventricular mechanical dyssynchrony, compared IVMD, SPWMD, Tmsvl6-SD and SDI, RVIT septal pacing group was better than the RVOT septum pacing group, and SPWMD, Tmsvl6-SD, SDI showed significant differences between two groups, especially SPWMD dose(P= 0.007); and these parameters were shortest while pacing in the lower mid-septum of RVIT tract.5、There were correlations of inter-ventricular dyssynchrony with PQRSd (r=0.429,P=0.041), but the correlation between intraventricular mechanical and electrical dyssynchrony was weak.Conclusion:1、When implanted the right ventricular septal electrodes, the paced QRS vector of leads Ⅲ and QRS transition in the precordial leads could predict the right ventricular electrode in septal of near apex, While pacing in the septal of near apex, has a wider QRS duration, suggesting that this pacing site could harmful to cardiac function. Therefore, when the right ventricular septal electrodes was implanted, except for meet the X-ray image standard, the following are significant:the paced QRS vector in leads Ⅲ and the QRS transition in the precordial leads.2、In the acute period, when pacing in RVIT septal, it can get better inter- and intra-ventricular dyssynchrony than pacing in RVOT septal, in particular, the intra-ventricular dyssynchrony has most obvious advantages. So, RVIT septal is the better choice of pacing.3、The PQRSd was shortest while pacing in the lower mid-septum of RVIT tract, and ventricular dyssynchrony was also better than the septal of near apex and RVOT septal. So, lower mid-septum of RVIT tract was the best choice of pacing site.